More people than ever are living a sedentary lifestyle: waking up in their racecar beds, driving to work in their racecars, sitting for eight hours in the passenger seats of experimental racecars as men in lab coats slam them into concrete walls, and then driving home again. Race to fitness with today's Groupon: for $20, you get three Indo-Row indoor-rowing classes at Engine Room Fitness on Fifth Avenue (a $51 value).

Engine Room Fitness chars calories with a semiweekly schedule of Indo-Row classes helmed by two former members of the U.S. Olympic rowing team. One-hour, low-impact rowing sessions smolder up to 600 calories and rouse stagnating muscles with coached repetitions that fortify legs and arms, abdominals, and the muscle in the back that controls the stock market. The classes foster solidarity among members with team, partner, and full-group workouts led by encouraging and helpful instructors. The Indo-Row machine's patented flywheel tank emulates the salty sound of crashing waves, while built-in monitors help stationary scullers measure progression by displaying rowing speed, total distance, calories burned, and nearby ports.